John 8:47
47 He that is of God heareth God’s words: ye therefore hear them not, because ye are not of God.
People will go to church, set in the pew, but never take to heart any of the word of God. Most will get upset if the pastor teaches on something within their life and calls it a sin. They will pout and leave and go find another church to tickle their ears. They do this because they are not of God. They want the image of being in church, but do not want to follow the teaching laid out within the bible. All you can do is pray for them, because even though they set within your congregation, they are still lost and undone without God. When they leave your church to find another one, just pray that God will open their eyes to the truth. Pray that they learn to hear and take to heart the word of God.